Synchronizing apparatus for alternators.



W 0 D w w SYNGHRONIZING APPARATUS FOR ALTERNATORS.

APPLIOATION FILED JULY 19.1900.

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PATENTBD MAY 12, 1903.

. 4 'F. T. DOW. SYNGHRONIZING APPARATUS FOR ALTERNATORs.

LPPLIOATION FILED JULY 19, 1900.

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UNITED STATES Patented May 12, 1903.

PATENT OFFICE.

FRED T. DOW, OF SOHENEOTADY, NEVVYORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, CORPORATION OF NEW YORK.

SYNCHRQNIZING APPARATUS FOR ALTERNATORS.

SPECIFICATION forming part of Letters Patent No. 727,601, dated May 12, 1903.

I Application filed July 19, 1900. Serial No. 24,150. (No model.)

To all whom it may concern.-

Be it known that I, FRED T. DOW, a citizen of the United States, residing in the city of Schenectady, county of Schenectady, and State of New York, have invented certain new and useful Improvements in Synchronizing Apparatus for Alternators, (Case D.1,447,) of which the following is a specification.

v In the distribution of alternating currents it becomes necessary in controlling the dynamo-electric machinesas, for example, to increase the capacity of a station or distributingpointto throw upon the distributing bus-bars auxiliary sources of alternating current. In order to prevent a'maohine so cut in from absorbing current and running as a motor, it is necessary to connect it with the common mains or bus-bars at a moment when its phases synchronize with those of the machines already delivering energy. It is therefore customary before throwing the switch to connect the auxiliary machine with the bus bars to bring it up to speed gradually and watch a phase-indicating device for the preoise moment when its phases register with those of the machines already in circuit.

It is the object of my invention to provide for cutting in an auxiliary source of alternating current by means more simple than those ordinarily employed, and to this end I employ a synchronizing-circuit common to all the machines of the station, substation, or distributing-point, said circuit containing any desirable phase-indicator, such as an incandescent lamp or a voltmeter, or both, and

upon which may be imposed potential from any pair of alternators in the station. In operative relation to this circuit is a plurality of step-down transformers connecting, respectively, with the several machines, any one of which may be cut into the circuit by means of a simple one-point plug forced into a socket, so as to bridge two contacts, which normally complete the metallic integrity of the circuit. Thus I provide a synchronizing organization consisting of a single circuit and a series of simple plug-switchesby which potential may be imposed thereon from the several machines.

The novel features of my invention will be hereinafter more specifically described, and will be definitely indicated in the claims appended to this specification.

In the accompanying drawings, Figure 1 is a diagram of a distributing system embodying my improvements. Figs. 2 and 3 are views in side elevation and cross-section, respectively, of a switch-plug suitable for use in my organization, and Fig. 4 is a modification of the system.

- 1 2 3 4 represent a plurality of sources of alternating current, and 5 5 5 a plurality of bus-bars with which they connect in parallel through three-point switches 6 6 6 6. I have shown by way of example a triphase organization. The invention, however, as will be evident to those skilled in the art, is in no wise restricted to such use and may be employed in connection with single-phase machines or polyphase machines of any order.

Oonnected'to the leads from the several machines are the primary windings of a plurality of step-down transformers 7 7 7 7, the connections being made with similar brushes of the several machines. The secondaries of these transformers connect with normally open contact-springs 8 9 8 9 860., mounted upon the switchboard or other support in conjunctive relation to pairs of normally closed contacts 10 ll 1O 11, &c., connected in series relation, as indicated in diagram, to a synchronizing-circuit 12, through which is supplied any desired phase-indicator. I have shown in the drawings a pair of incandescent lamps 13 and a voltmeter 14:, both of which may be employed and both of which, indeed, I preferably employ in practice, it being usual to place the lamps at convenient points on the board or the machines, or both, and use a single voltmeter located at a central point of the board. The lampsmay, if desired, be distributed, as shown in Fig. 4., so as'to be adjacent to the control-point of each machine, as 'seen at 13 13 I It will be noted that the synchronizing-circuit 12 is normally closed, and a plug, by which the machines are connected with the circuit, is adapted to separate the contacts 10 11 10 11, &c., effecting the cross connection between the springs 8 9 and 10 11, respectively. This may be effected by a plug of simple construction, as indicated in Figs. 2 and 3, in which an insulating-pin has mounted in or on its sides two metal strips 15 15, insulated from one another and sufficient in length to cross-connect spring-contacts 8 10 and 9 11 when the plug is inserted in the socket in the switchboard upon which these springs are mounted. Thus it will be seen that the metallic integrity of the synchronizing-circuit is at all times complete and that the withdrawal or insertion of the plug to connect a machine in no wise disturbs it in this respect, whereas the transformer-circuit of all the machines is open unless the plug by which the test is being made is inserted so as to bridge the testing-contacts.

Let us assume that machines 1, 2, and 3 are in service and it be desired to cut in an auxiliary machine 4 to meet an increased load on the system. The switches 6 6 6 will have been already connected with the distributing bus-bars, and the operator will insert a plug in some one of the sockets corresponding to the transformers 7, 7, or 7", respectively, thereby delivering potential on the synchronizing-circuit 12, the phases being the same as those on the bus-bars 5 5, 850. An auxiliary plug is then inserted in the contacts corresponding to the transformer 7, thereby imposing the potential of this transformer on the synchronizing-circuit 12 in series relation to that already on the circuit. Assuming that plugs corresponding to transformers 7 and 7 are inserted in the synchronizing-circuit, we may trace the path of current from the right side of the low-potential coil of 7 through spring-contact 9 across the conducting-strip on the switch-plug, say 15, to contact-spring 11 right-handedlyin the synchronizing-circuitto spring-contact 10 ,and thence by the conductive strip in the plug of that socket to contact-spring 8, through the secondary of transformer 7, to spring 9, across the companion contact-strip of the plug, say 15, thence to the voltmeter or other phaseindicator, returning to the starting-point through the contacts 10 11 10 11 and to contact 10, across the conducting-strip 15 of the switch-plug to spring 8 to the terminal of the transformer 7 Thus the two transformer-windings are in series relation to the phase-indicator, and when they reach the point of maximum potential, or at least a point of phase identity, the switch 6is thrown and the generator 4 connected to the distributing-circuit. It is customary to connect the machine when the lamps indicate maximum potential and when the voltmeter-needle attains a condition of minimum vibration. The transformers 7 7, 850., are of course small in size and cheap in construction and adapted to deliver current of Very small volume.

While I have shown a transformer for each machine, it will be evident to those skilled in the art that but two transformers would serve break-points in series with potential derived from the bus-bars.

2. Means for synchronizing alternating-current machines, comprising a synchronizingcircuit containing a phase-indicator, a plurality of normally closed break-points in said circuit, and a single-point plug-switch adapted to separate the break-points to impose electromotive forces derived from any pair of machines in series on said circuit.

3. Means for synchronizing alternating-current machines,'comprising a synchronizingcircuit containing a phase-indicator, a plurality of potential transformers, normally closed break-points in the circuit, and plugswitches adapted to open said break-points and connect the transformers in series, Whereby any machine may be synchronized with the machines already connected with the distribution-circuit.

4. Meansforsynchronizingalternating-current machines, comprising switches for independent connection of the machines with the distribution-circuit, a synchronizing-circuit containing a plurality of normally closed break-points, a plurality of normally open break-points to receive the potential of different machines, and plug-switches to open the closed break-points and connect them with the open break-points.

5. Meansforsynchronizingalternating-current machines, comprising switches for independent connection of the several machines with the distribution-circuit, an independent synchronizing-circuit containing a phase-indicator and a plurality of normally closed plug-sockets, potential-transformers for the machines, and means for plugging a transformer corresponding to a machine to be synchronized into circuit with one corresponding to a machine already operating at said sockets.

6. Means for synchronizing alternating-cur rent machines, comprising a synchronizingcircuit including a phase-indicator, switchluu contacts in said circuit corresponding respectively to a machine to be synchronized and those already operating, corresponding contacts deriving potential from the machine already operating, and single-point plugswitches carrying insulated metallic bridges for connecting the several pairs of contacts.

In Witness whereof I have hereunto set my hand this 17th day of July, A. D. 1900.

FRED T. DOW.

Witnesses:

BENJAMIN B. HULL. MABEL E. JAcoBsoN. 

